The present disclosure relates to the subject matter disclosed in German application No. 100 40 024.8 of Aug. 16, 2000, which is incorporated herein by reference in its entirety and for all purposes.
The invention relates to a cutting machine comprising a machine frame, an anvil roller rotatably mounted on the machine frame about a rotary axis and having an anvil surface, a cutting tool mounted on the machine frame for rotation about a rotary axis, with a cutter interacting with the anvil surface and with supporting rings which are held on the cutting tool and support it relative to the anvil roller with their supporting ring surfaces and/or vice versa.
A cutting machine of this type is known e.g. from German patent application 198 34 104.0.
The problem with such cutting machines is that the cutter itself wears down in the course of time, and even slight wear on it may lead to an inadequate cutting effect with sensitive webs of material.
The object underlying the invention is therefore to improve a cutting machine of the generic type so that the quality of the cutting effect can be maintained even when the cutter becomes worn.
In a cutting machine of the above type this object is solved, according to the invention, in that the diameter of the surface of each supporting ring is adjustable by radial stretching of the supporting ring within the range below an elastic expansion limit of its material by means of an expansion device.
The advantage of the solution according to the invention is thus that the possibility has been created of making the diameter of the supporting ring surfaces variable, as a means of allowing for changes in the radial extent of the cutter and particularly for wear on it.
In the solution according to the invention, initially with a new, i.e. unworn cutter, the supporting ring is stretched to the maximum, though still within the range below its elastic expansion limit, so that the supporting ring surface has its maximum diameter. When the cutter becomes worn the expansion can be reduced by the adjustable expansion device; as the stretch is within the range below the elastic expansion limit of the supporting ring, that ring contracts automatically through its elastic action when the expansion device is reset to less expansion, and the diameter of the supporting ring surface can thus be reduced according to the wear on the cutter.
The solution according to the invention may therefore have the expansible supporting rings according to the invention on the cutting tool or on the anvil roller or on both; in the latter case a supporting ring on the cutting tool and a corresponding supporting ring on the anvil roller will have their surfaces in contact, so that twice the adjustment range can be obtained.
The expansion device might for example operate hydraulically, comprising e.g. hydraulically actuated clamping jaws. A particularly favorable solution is for the device to have interacting wedge surfaces which are adjustable in their position relative to each other, in order to expand the supporting ring adjustably.
The wedge surfaces might e.g. be simple (flat) surfaces, in which case the supporting ring could be stretched (i.e., expanded) evenly by a plurality of wedge surfaces.
A particularly favorable solution provides for at least one of the wedge surfaces to be in the form of a conical surface relative to the rotary axis. A conical surface of this type allows particularly uniform expansion of the supporting ring.
However it is particularly beneficial for both wedge surfaces to be in the form of conical surfaces relative to the rotary axis, in order to expand the supporting ring as evenly as possible and especially to obtain uniform radial rigidity for the support between the cutting tool and anvil roller.
In a particularly favorable solution in respect of adjustability, one the wedge surfaces is an internal one and the other is a corresponding external one, and they are movable relative to each other in a direction parallel with the rotary axis to adjust the expansion of the supporting ring.
A particularly appropriate way of adjusting the expansion with the expansion device is for an internal wedge surface to be arranged on a radially expansible element carrying it; that element allows the supporting ring to be supported radially in a simple manner.
A particularly appropriate solution provides that, in all diameter adjustments of the supporting ring surfaces the internal wedge surface is seated on the external wedge surface with elastic expansion of the element carrying the internal surface, so that the expansion device operating with the wedge surfaces does not allow any play or radially reduced rigidity through the superimposed wedge surfaces, which would have a negative effect on the support between the cutting tool and the anvil roller.
In an advantageous embodiment the external wedge surface is provided on an expansion member arranged on the cutting tool or the anvil roller; this expansion member may be either part of the cutting tool or the anvil roller or may be a separate part placed on and supported against the cutting tool or anvil roller.
The expansion member could itself have a certain radial elasticity. In order to obtain defined expansion of the supporting ring it is however advantageous for the expansion member to be substantially non-elastic in a radial direction.
Particularly simple adjustment of radial expansion can be obtained if the radially expansible element carrying the internal wedge surface and the expansion member are movable relative to each other in the direction of the rotary axis, so that the required amount of expansion can be set.
It is particularly beneficial if the radially expansible element carrying the internal wedge surface and the expansion member may be fixed in the various positions relative to each other on the cutting tool or on the anvil roller.
Especially simple adjustability can be obtained if the radially expansible element and the expansion member may be positioned varying distances away from an end face of the cutting tool or the anvil roller, in order to hold these in the required position relative to each other which predetermines the expansion.
This can be engineered particularly appropriately if the radially expansible element or the expansion member may be positioned by a distance element different distances away from the end face of the cutting tool or on the anvil roller, so that the necessary relative positioning of the expansion member and radially expansible element can be defined in a simple manner.
It would be possible to construct the expansion device with an expansion member and a radially expansible element provided, these parts then interacting to expand the supporting ring in a radial direction.
A structurally particularly simple and hence cost-effective solution is for the radially expansible element to be the supporting ring itself, so that the supporting ring itself is part of the expansion device provided that the ring carries the internal wedge surface.
In a structurally especially simple embodiment the external wedge surface is seated on a central expansion member which is surrounded by the supporting ring.
To obtain easy adjustability of the expansion but also stable fixing of the supporting ring on the cutting tool, the supporting ring may be braced against an end face of the cutting tool or of the anvil roller, in order not only to brace the supporting ring in a radial direction but also to put it in a defined position in a plane perpendicular to the rotary axis, thus achieving extremely precise bracing of the cutting tool and anvil roller relative to each other.
The solution according to the invention can be obtained particularly easily if the supporting ring can be positioned against the cutting tool an adjustable distance away from the end face of the cutting tool or anvil roller according to the elastic expansion state.
It is particularly appropriate if the supporting ring can be positioned various distances away from the end face by the distance element, as clamping is then still possible, enabling the supporting ring to be held securely to the cutting tool or anvil roller.
In addition the above-mentioned object can be solved according to the invention by a cutting tool rotatable about a rotary axis, with a cutter which interacts with an anvil surface of an anvil roller rotatable about a rotary axis, and with supporting rings which are held to the cutting tool and support it relative to the anvil roller with their supporting ring surfaces, in that in the case of each supporting ring the diameter of the supporting ring surface is adjustable by radial expansion of the supporting ring within the range below an elastic expansion limit of its material, by means of an expansion device.
The above-mentioned object can further be solved according to the invention by an anvil roller rotatable about a rotary axis, comprising an anvil surface which interacts with a cutter of a cutting tool rotatable about a rotary axis, and further comprising supporting rings which are held to the anvil roller and support it relative to the cutting tool with their supporting ring surfaces, in that in the case of each supporting ring the diameter of the supporting ring surface is adjustable by radial expansion of the supporting ring within the range below an elastic expansion limit of its material, by means of an expansion device. Other features and advantages of the invention are the subject of the following description and of the drawings of an embodiment.